For providing passengers with safety protection in accidents, an air bag system has become a standard device of modern day vehicles.
The gas inflation devices of the prior art for car air bags are categorized into full pressurized-gas type, gas-generant type, and hybrid type. The full pressurized-gas type directly uses a high-pressure gas stored in a high-pressure container to inflate an air bag. It is a disadvantage that this mechanism needs a larger quantity of gas and therefore the weight and size of the gas container cannot be too small. On the other hand, the gas-generant type uses propellant or pyrotechnics to generate a high-pressure gas to inflate an air bag; therefore, the size of the inflation device can be made small. But the solid impurities in the gas, a byproduct of combustion, are hazardous to humans and the environment. It is a further disadvantage that the hot gas may burn an air bag during a charging process. The hybrid type uses less amount of propellant or pyrotechnics to heat up and thereby expand a gas stored in a high-pressure container; therefore, the gas container can be small.
It is a further consideration that a pressure-resisting disc, without further supportive components, seals the conventional high-pressure gas container. Therefore, the thickness of the pressure-resisting disc should be precisely designed that it not only sustain the gas pressure in the container but also can be easily broken when the charging process is activated. An improperly designed pressure-resisting disc may break up accidentally and cause a hazard to the passengers.